Thales

Sextant Avionique

Thomson-csf Sextant

Alain Renard

Jean-Pierre Schlotterbeck

Xavier Lacondemine

Bertrand Baillon

Patrice Guillard

Franck Letestu

Estelle Kirby

Valéry Leblond

Bernard Fouilland

Stéphane Monrocq

Damien Korpet

Nelly Suaud

Marc Revol

Method of measuring the velocity of an aircraft at a given instant, by laser Doppler anemometry, by performing the steps of acquiring a backscattered signal on at least three oriented line-of-sight axes, and calculating the spectrum of the backscattered signal on each of the line-of-sight axes. Further, acquiring an additional backscattered signal on at least one additional line-of-sight axis (X) not coincident with one of the three first line-of-sight axes (X, X, X), and calculating the spectrum of the backscattered signal on the additional line-of-sight axis (X). Several candidate velocity vectors ({right arrow over (V)}c) and of the projections of the candidate vectors on at least one line-of-sight axis (X, X, X, X) are calculated. The consistency of the candidate vectors ({right arrow over (V)}c) is calculated as a function of their projections and as a function of each spectrum of the corresponding backscattered signal on the respective calculation axis (X, X, X, X). The measured velocity vector ({right arrow over (V)}c) is chosen from among the candidate velocity vectors ({right arrow over (V)}c).

Method of measuring the velocity of an aircraft by laser doppler anemometry

The present invention concerns a single-particle LIDAR anemometry method and system comprising the continuous emission of one or more light beams through a gas containing particles, said beam being focused onto a measurement volume, a step of detecting a signal backscattered by particles passing through said volume, the method being characterized in that it comprises at least the following phases: A notable application of the invention is for the measurement of the airspeed of an aircraft.

Single-particle LIDAR anemometry method and system

The invention relates to a radiofrequency receiver, notably for satellite positioning applications, needing to operate in an environment where interference is dense, notably when it involves pulses transmitted by DME beacons. Below the useful signal suppression threshold, amplitude or power are inverted to improve the dynamic interference response time. Advantageously, the useful signal suppression threshold and the set point power or amplitude are determined by analyzing the amplitude or power probability density function in its part enriched with low amplitude/power samples.

Processing of interference on a radiofrequency signal by power inversion

The present invention relates to a frequency shifter in an optical path containing a pulsed laser source, and it is characterized in that it comprises at least one frequency shifter () containing an optical propagation medium, the optical path length of which is modified according to the desired frequency shift during at least one pulse among n consecutive pulses from the laser, where n&#x2267;1.

Frequency shifter in an optical path containing a pulsed laser source

The invention relates to a device for measuring a Doppler frequency shift, including an optical signal channel delivering a signal light beam illuminating a reference medium; and a reference channel delivering a reference light beam for detecting the Doppler frequency shift. The frequency shift is determined from the difference in frequency between the light signal illuminating the reference medium and the light beam returned by the reference medium. The device includes at least two light radiation sources, preferably lasers, with one light radiating source generating the light beam for the signal channel and the other source generating the light beam for the reference channel.

Optical device for measuring a doppler frequency shift

The present invention relates to a frequency shifter in an optical path containing a continuous laser source, and it comprises at least two frequency shift modules placed in parallel and each containing an optical propagation medium, the optical path length of which is modified according to the desired frequency shift, each of these modules being controlled separately, this shifter comprising a switch () which is connected to the outputs of these modules and is controlled so as to choose, at each instant, the module providing the desired frequency shift, the switch delivering, at its output, a continuous optical beam whose frequency is adjusted by contiguous sections.

Frequency shifter in an optical path containing a continuous laser source

Apparatus and methods degarble a received broadband radio signal using spatial filtering. The apparatus and methods use various garbled versions of the signal delivered by parallel processing chains assumed to have the same transfer function. Automatic equalization (), at the level of the outputs of the processing chains (to), is performed before the spatial filtering (). The automatic equalization reduces disparities, innate or originate from drifts over time, between processing chains (to), and uses a local test signal generator ().

Interference suppression, method and device, in reception, for a wideband radio signal

The invention relates to the improving of the resistance to intentional or unintentional jamming, of a receiver of spread spectrum radio signals transmitted by polarized wave. It consists in furnishing receiver with an array antenna composed of elementary antennas having at least one so-called matched output path MP sensitive to the polarization of the polarized wave used for the transmission, certain furthermore having a second so-called cross path CP sensitive to a polarization orthogonal to that of the polarized wave used for transmission and in performing first individual antijamming processings by polarimetric filtering on each of elementary antennas with matched MP and cross CP output paths then, globally, at the level of reception signals obtained and of reception signals of elementary antennas without cross output path CP utilized, a second general antijamming processing by spatial filtering. Moreover, the invention can integrate additional antijamming processings by temporal or spectral filtering.

Anti-jamming method for spread-spectrum radio signal receivers

The invention allows the detection and processing in a radio signal received by a receiver, of any signal of 'pulsed' type present in radio signals applied to the input of a radiofrequency receiver, the receiver having an analogue/digital converter for performing the coding into digital on N bits of P successive samples of the analogue signal applied to the input of the receiver and a computer for processing the said digital signals, characterized in that on the basis of a histogram of the rate of occupancy of the digitized samples, graded in ranges Fx of amplitude-increasing sample levels, is determined, from among the ranges Fx, a range Fn onwards of which the total number of digitized samples Nnor contained in the ranges Fn and those below Fn is greater than or equal to a normality threshold Nn, Nn being a number predetermined as a function of the sensitivity of the detection of pulsed signals that one wishes to achieve.

Method of detecting and processing pulsed signals in a radio signal

The invention proposes a method of rejecting interference disturbing the reception by means of a reception system, of a signal emanating from a transmission system, the method comprising a calculation for weighting the signals S(t), i varying from 1 to K, emanating from the reception system, based on the intercorrelation matrix Rfor the signals S(t), the matrix Rcomprising on its diagonal the autocorrelation terms of the signals S(t). The method is chiefly one wherein the weighting calculation comprises a step consisting in modifying the autocorrelation terms of the diagonal of the matrix R

Method of rejecting interference disturbing the reception of a satellite radio signal

The invention relates to a method of suppressing pulsed signals in particular of DME or TACAN type present in the radio signals received (Ue) by a radio-frequency receiver, characterized in that the reception frequency band of the receiver is divided into frequency sub-bands corresponding to the transmission channels of the pulsed signals, in that the presence of the pulsed signals and the transmission channel of said pulsed signals in the frequency sub-bands are detected, and in that the frequency sub-band comprising the detected pulsed signals is filtered over the duration of the pulsed signal so as to eliminate said pulsed signals pulse type.

Device and method for the suppression of pulsed wireless signals

An analog circuit for receiving satellite signals through an antenna. The circuit includes frequency transposition circuits and an analog/digital converter. Each frequency transposition circuit includes at least two frequency dividers of which due first is programmable so as to provide division ratios 140 and 143. The other divider provides one of the division ratios of 10 or 11. A third divider provides ratios of 3, 5, 7 or 8. These division ratios enable a single analog integrated circuit topography to allow a large number of possible applications including civil or military receivers operating on the GPS constellation or on the GLONASS constellation.

Signal analog processing circuit for satellite positioning receiver

A method for position determination with the aid of GPS satellites, including reception processing of a GPS satellite signal L2 modulated by an encrypted code Y having a key not available from the GPS satellite, so as to assess a delay of the signal L2 with respect to the signal L1 and to deduce therefrom the magnitude of the ionospheric effect so as to take account thereof and improve the accuracy of the location finding. This processing includes reducing the signal L2 to a lower band and in despreading the signal L2 by means of the non-encrypted code P produced locally in reception by a local generator of a non-encrypted spreading code P synchronized with the code Y (encrypted P) transmitted, with the aid of a phase lock loop with three parallel paths: a first path demodulated by a precise version of the locally produced non-encrypted spreading code P, a second advanced path demodulated a first time by an advanced version of the locally produced non-encrypted spreading code P and a second time by the demodulated signal of the precise path, and a third delayed path demodulated a first time by a delayed version of the locally produced non-encrypted spreading code P and a second time by the demodulated signal of the precise path, synchronization being achieved by searching for an equality of power of the carrier of the signal L2 at the output of the advanced and delayed paths.

Method and device for reception processing of a GPS satellite L2 signal

Receiver for determining a position on the basis of satellite networks

This receiver comprises a signal processor using the correlation of the received composite signal with early/late, locally generated pseudo-random codes. The code generator sends its signals to a delay line whose evenly spaced out outputs (E2, E1, P, L1, L2) are combined according to the relationship:

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Chabeuil, France

Alain Renard